1. Field of the Invention
The present invention relates to a display apparatus, such as a projection type display apparatus for displaying computer images, video images, etc. on a large screen.
2. Description of the Related Art
Recently, the purposes of use of projection type display apparatuses for displaying computer images in presentations using computers are diversified, and there is a demand for a projection type display apparatus which provides optimum color purity, color balance, illuminance, etc. according to the purpose of use.
FIG. 8 shows the construction of a conventional projection type display apparatus. In FIG. 8, white light emitted from a light source portion 101 is condensed by a reflector 102, passes through fly-eye lenses 103 and 104, a polarization transformation element 105, and a condenser lens 106. Then, it travels by way of a mirror M1 and is separated into three color lights of R, G and B by dichroic mirrors DM1 and DM2, transmitted through condenser lenses 107G and 107B and a relay lens system 107R, transmitted through dichroic filters DF(G) and DF(R), and transmitted through image display elements 108R, 108G and 108B before the color lights of R, G and B are synthesized into one, the image displayed on the image display elements being projected in an enlarged state onto a screen or the like (not shown) by a projection lens 109.
As the light source, a discharge lamp such as a metal halide lamp or a mercury vapor lamp is used. FIG. 9 shows an example of the spectral distribution of a white light source.
As shown in FIG. 9, generally speaking, a white light source has a continuous intensity distribution in the visible light wavelength range of 400 nm to 700 nm. In a projection type display apparatus as shown in FIG. 8, this white light is separated into color lights of R, G and B in a color separation system. At this time, when light component in the wavelength range of 570 nm to 600 nm is taken in the green color light component, the green is turned into yellow, making it difficult to express the pure green color.
Further, when light component in the wavelength range of 570 nm to 600 nm is taken in the red color light component, the red is turned into orange, making it difficult to express the pure red color. In view of this, in the illumination system of the projection type display apparatus, a dichroic filter, etc. are provided on the incident side of the image display elements in addition to the dichroic mirrors DM1 and DM2 to remove the light of the wavelength range of 570 nm to 600 nm so that the light of the wavelength range of 570 nm to 600 nm may not reach any of the image display elements. FIG. 10 shows the spectral distribution of white light synthesized by a dichroic prism DP when light of the wavelength range of 570 nm to 600 nm is removed.
In the construction of FIG. 8, the spectral transmittances of the dichroic mirrors DM1 and DM2 are shown in FIGS. 11 and 12, and the spectral transmittances of dichroic filters DF(G) and DF(R) when light of the wavelength range of 570 nm to 600 nm is removed by providing the dichroic filters DF(G) and DF(R) are shown in FIGS. 13 and 14. Here, there is a technique in which at least one of the dichroic filters DF(R) and the DF(G) can be inserted and removed into and from the optical path, making it also possible to display a color image with no dichroic filter. According to this technique, the dichroic filter is inserted and removed into and from the optical path to thereby vary the purity of the corresponding color to vary the light quantity, whereby it is possible, in a single projection type display apparatus, to select between a color-purity-emphasized (color-reproduction-emphasized) display form (normal mode) and a brightness-emphasized display form.
However, the construction in which the dichroic filter is inserted or removed to thereby vary the purity of the corresponding color to vary the light quantity, has the following problems.
1. When a user of the projection type display apparatus has inserted or removed the dichroic filter into or from the optical path, it is possible for the user to recognize whether the apparatus is in the color-purity-emphasized mode or the brightness-emphasized mode. However, if after this user has inserted or removed the dichroic filter, another user uses the projection type display apparatus to display an image from which it is difficult to recognize whether the apparatus is in the color-purity-emphasized mode or the brightness-emphasized mode, the apparatus might be used in a state not suited for the purpose of use of the other user.
2. When the dichroic filter is removed from the optical path (when it is on standby outside the optical path), the quantity of light impinging upon the image display elements is larger than when the dichroic filter is in the optical path, so that the amount of heat generated at the polarizing plates provided in front of and behind the image display elements also substantially increases, with the result that the temperature in the vicinity of the image display elements rises, thereby adversely affecting the characteristics of the image display elements and the polarizing plates.
Accordingly, it is an object of the present invention to provide a display apparatus capable of solving the above problems 1 and 2 separately or simultaneously.
In a first aspect of the present invention, there is provided a display apparatus of the type which forms a color image by modulating a plurality of lights, different from each other in color, by one or more display elements. The display apparatus comprising means for obtaining a plurality of different display forms by changing the color purity of at least one of the plurality of lights, and means for supplying information on the display forms.
In a second aspect of the present invention, there is provided a display apparatus of the type which forms a color image by modulating a plurality of lights, different from each other in colors, by one or more display elements. The display apparatus comprising means for changing the color purity of at least one of said plurality of lights by inserting or extracting a wavelength selection element into or out of the optical path of at least one of said plurality of lights or changing the attitude of the wavelength selection element, and means for supplying information as to whether the wavelength selection element is in the optical path of the at least one of the plurality of lights or information on the attitude of the wavelength selection element in the optical path of the at least one of the plurality of lights.
In a third aspect of the present invention, there is provided a display apparatus, wherein said means for supplying information includes a display means formed by an LED, a liquid crystal device, etc.
In a fourth aspect of the present invention, there is provided a display apparatus of the type which forms an image by modulating light by one or a plurality of display elements, said display apparatus comprising cooling means for cooling the display elements, the cooling means being capable of varying its cooling capacity according to variation in the display form of the image.
In a fifth aspect of the present invention, there is provided a display apparatus of the type which forms an image by modulating light by one or more display elements, with the display apparatus comprising cooling means for cooling the display elements and means for varying the quantity of light impinging on the one or more display elements. The cooling capacity of the cooling means with respect to the one or more display elements is varied according to variation in the quantity of light.
In a sixth aspect of the present invention, there is provided a display apparatus of the type which forms a color image by modulating a plurality of lights, different from each other in color, by one or more display elements. The display apparatus comprises cooling means for cooling the display elements and means for obtaining a plurality of display forms by changing the color purity of at least one light of the plurality of lights, wherein the cooling capacity of the cooling means is varied with respect to the display elements modulating said at least one of said plurality of lights according to variation in the color purity of at least one of said plurality of lights.
In a seventh aspect of the present invention, there is provided a display apparatus of the type which forms a color image by modulating a plurality of lights different from each other in color by one or a plurality of display elements. The display apparatus comprises cooling means for cooling the display elements and means for varying the color purity of at least one light of the plurality of lights by inserting or removing a wavelength selection element into or from the optical path of the at least one light or varying the attitude of the wavelength selection element. The cooling capacity of the cooling means with respect to the display elements modulating said at least one light is varied according to whether the wavelength selection element is in the optical path of said at least one light or not or according to variation in the attitude of the wavelength selection element in the optical path of said at least one light.
In an eighth aspect of the present invention, there is provided a display apparatus wherein the cooling means is an air cooling type cooling means, the variation in the cooling capacity being variation in air flow rate with respect to the display element.
In a ninth aspect of the present invention, there is provided a display apparatus wherein the cooling means is a water cooling type cooling means, the variation in the cooling capacity being variation in flow rate with respect to the display element.
In a tenth aspect of the present invention, there is provided a display apparatus of the type which forms a color image by modulating a plurality of lights, different from each other in color, by one or more display elements. The display apparatus comprises air-cooling means for air-cooling the display elements, means for varying the color purity of at least one light of the plurality of lights by inserting or removing a wavelength selection element into or from the optical path of the at least one light or varying the attitude of the wavelength selection element, and means for supplying information on the position or the attitude of the wavelength selection element with respect to the optical path of the at least one light. The air flow rate of the air-cooling means is varied with respect to the display elements modulating the at least one light according to whether the wavelength selection element is in the optical path of the at least one light or not or according to the attitude of the wavelength selection element in the optical path of the at least one light.
In an eleventh aspect of the present invention, there is provided a display apparatus wherein said means for supplying information is provided with means for detecting that the wavelength selection element is in the optical path of said at least one light or that it is in a predetermined attitude and for lighting a lamp.
In a twelfth aspect of the present invention, there is provided a display apparatus wherein the wavelength selection element is an element which transmits visible light of a wavelength longer than a predetermined wavelength and blocks visible light of a wavelength shorter than that or an element which transmits visible light of a wavelength shorter than a predetermined wavelength and blocks visible light of a wavelength longer than that.
In a thirteenth aspect of the present invention, there is provided a display apparatus wherein the wavelength selection element is an edge filter, a band pass filter or a band cut filter.
In a fourteenth aspect of the present invention, there is provided a display apparatus comprising a plurality of dichroic mirrors separating white light from a light source into the plurality of lights of different colors consisting of red, green and blue.
In a fifteenth aspect of the present invention, there is provided a display apparatus wherein the display elements are arranged in correspondence with the red, green and blue lights, and wherein there are provided a plurality of dichroic mirrors for synthesizing image light from a plurality of display elements modulating the red, green and blue lights.
In a sixteenth aspect of the present invention, there is provided a display apparatus wherein the display elements include three pixel groups, respectively corresponding to the red, green and blue lights, and micro lens arrays condensing lights of the colors corresponding to three pixels of each group.
In a seventeenth aspect of the present invention, there is provided a display apparatus further comprising a projection lens for projecting the image of the display portions of the display elements onto a screen, a wall or the like.
In an eighteenth aspect of the present invention, there is provided a projection type display apparatus comprising image display elements, a light source for illuminating the image display elements, at least one first optical element for color-separating the light from the light source into at least two color lights and causing them to impinge upon the image display elements, at least one second optical element for synthesizing the lights output from the image display elements into one, and a lens upon which the light from the at least one second optical element impinges and which projects the image displayed by the image display elements in an enlarged state. A third optical element which transmits visible light of a wavelength shorter than that or vice versa, can be inserted or removed in or from the optical path between the at least one first optical element and the at least one second optical element, and there is provided means for supplying information as to whether the third optical element is in the optical path or not.
In a nineteenth aspect of the present invention, there is provided a projection type display apparatus wherein the means for supplying information as to whether the third optical element is in the optical path or not consists of means for detecting that the third optical element is in the optical path and indicating this by an indicating lamp.
In a twentieth aspect of the present invention, there is provided a projection type display apparatus comprising image display elements, a light source for illuminating the image display elements, a first optical element for color-separating the light from the light source into at least two color lights and causing them to impinge upon the image display elements, a second optical element for synthesizing the lights output from the image display elements into one, and a lens upon which the light from the second optical element impinges and which projects the image displayed by the image display elements in an enlarged state. A third optical element which transmits visible light of a wavelength shorter than that or vice versa, can be inserted or removed in or from the optical path between the first optical element and the second optical element, and there is provided means for changing the cooling condition of the image display elements upon which a larger or smaller quantity of light impinges according to whether the third optical element is in the optical path or not.
In a twenty-first aspect of the present invention, there is provided a projection type display apparatus wherein said means for changing the cooling state consists of a means for detecting the third optical element in the optical path and reducing the air flow rate of the cooling fan as compared to the condition in which the third optical element is not in the optical path.
In a twenty-second aspect of the present invention, there is provided an image processing apparatus comprising a display apparatus as claimed in one of Claims 1 through 21 and a computer for inputting image information to said apparatus.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments (with reference to the attached drawings).